226 DIFFRACTION OF LIGHT BY SPHERES OF SMALL RELATIVE INDEX [381
this point, nor heyond it, is there anything but a steady rise in the value of (13) as \ diminishes when R is constant. A fortiori is this the case when R increases and \ is constant.
An increase in the light scattered from a single spherical particle implies, of course, a decrease in the light directly transmitted through a suspension containing a given number of particles in the cubic centimetre. The calculation is detailed in my paper " On the Transmission of Light through an Atmosphere containing Small Particles in Suspension *," and need not be repeated. It will be seen that no explanation is here arrived at of the augmentation of transparency at a certain stage observed by Keen and Porter. The discrepancy may perhaps be attributed to the fundamental supposition of the present paper, that the relative index is very small [or rather very near unity], a supposition not realised when sulphur and water are in question. But I confess that I should not have expected so wide a difference, and, indeed, the occurrence of anything special at so great diameters as 10 wave-lengths is surprising.
One other matter may be alluded to. It is not clear from the description that the light observed was truly transmitted in the technical sense. This light was much attenuated—down to only 5 per cent. Is it certain that it contained no sensible component of scattered light, but slightly diverted from its original course ? If such admixture occurred, the question would be much complicated.
* Phil. Mag. Vol. XLVII. p. 375 (1899); Scientific Papers, Vol. iv. p. 397. 15 - du ............................ (17)